1. Field of the Invention
The present invention pertains to methods of treating fabric. More particularly, the present invention concerns methods of treating denim fabrics. Even more particularly, the present invention relates to methods of treating "faded" denim fabrics to reduce or minimize the yellowing thereof.
2. Prior Art
The popularity of denim articles of clothing, such as "blue jeans", is well known. One particular style of denim clothing which has achieved high popularity is the "faded", "stone-washed" or "washed-out" article.
As is known to those skilled in the art to which the present invention pertains, the processing of the denim article to achieve the "faded" look involves, treating the denim article with potassium permanganate.
The permanganate is introduced into the fabric either directly or through the use of permanganate-treated rocks or stones, which are, then, tumbled together to provide the "washed-out" or "stone-washed" or "faded" effect.
To neutralize the permanganate after treatment of the articles, traditionally, an "antichlor" is applied to the denim article. The "antichlor" is introduced, also, to minimize the yellowing of the fabric after washing or similar treatment.
Generally, the "antichlors" which are used to neutralize the permanaganate are either sodium dithionate or sodium bisulfite. While the dithionates or bisulfites are efficacious for neutralizing the permanganate certain side effects detract from their desirability.
The sulfite products, when introduced into a manufacturing plant effluent, tend to cause higher biological oxygen demand (BOD) readings since these compounds are oxygen scavengers. The higher BOD readings, thus, necessitate the installation of aerators, oxygenators or similar equipment in order to raise the oxygen in the effluent to meet environmental regulations. This increases the cost of manufacturing.
It is, therefore, readily apparent that there exists a need in the art for an "antichlor" which does not unnecessarily raise BOD readings and plant effluent and which minimizes yellowing of the fabric.